Blanks typically are a cartridge with no bullet. There is a brass case, and the base of the case has an area called the primer. The primer is an impact-ignited area, which when struck by the hammer of the gun ignites and in turn ignites the gunpowder. The bullet is a lead slug which is propelled down the barrel of the gun toward the target.
In a shotgun shell, the bullet is replaced by smaller round pellets, with the size of the pellets depending on what you're hunting. Shotgun cartridge cases are also paper instead of brass.
In a blank, the lead bullet is typically replaced by a paper or plastic wad the same size diameter (caliber)-- but at close range it can do serious damage.
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